def test_numeral():
from pypy.lang.prolog.interpreter.term import Term, Atom, Var
from pypy.lang.prolog.interpreter.engine import Engine
t = parse_file("""
numeral(null). % end of line comment
numeral(succ(X)) :- numeral(X). % another one
add_numeral(X, null, X).
add_numeral(X, succ(Y), Z) :- add_numeral(succ(X), Y, Z).
greater_than(succ(null), null).
greater_than(succ(X), null) :- greater_than(X, null).
greater_than(succ(X), succ(Y)) :- greater_than(X, Y).
""")
builder = TermBuilder()
facts = builder.build(t)
e = Engine()
for fact in facts:
print fact
e.add_rule(fact)
assert e.signature2function["add_numeral/3"].rulechain.rule.head.args[1].name == "null"
four = Term("succ", [Term("succ", [Term("succ",
[Term("succ", [Atom("null")])])])])
e.run(parse_query_term("numeral(succ(succ(null)))."))
term = parse_query_term(
"""add_numeral(succ(succ(null)), succ(succ(null)), X).""")
e.run(term)
var = Var(0).getvalue(e.heap)
print var, e.heap
# does not raise
var.unify(four, e.heap)
term = parse_query_term(
"""greater_than(succ(succ(succ(null))), succ(succ(null))).""")
e.run(term)
def test_run():
e = Engine()
e.add_rule(Term("f", [Atom.newatom("a"), Atom.newatom("b")]))
X = Var()
Y = Var()
e.add_rule(Term("f", [X, X]))
e.add_rule(Term(":-", [Term("f", [X, Y]),
Term("f", [Y, X])]))
X = e.heap.newvar()
e.run(Term("f", [Atom.newatom("b"), X]))
assert X.dereference(e.heap).name == "b"
e.run(Term("f", [Atom.newatom("b"), Atom.newatom("a")]))
def test_term():
X = Var()
Y = Var()
t1 = Term("f", [Atom.newatom("hallo"), X])
t2 = Term("f", [Y, Atom.newatom("HALLO")])
heap = Heap()
print t1, t2
t1.unify(t2, heap)
assert X.getvalue(heap).name == "HALLO"
assert Y.getvalue(heap).name == "hallo"
def newvar(self):
result = Var(self)
return result
def test_recursive():
b = Var()
heap = Heap()
b.unify(Term("hallo", [b]), heap)
def test_unify_var():
b = Var()
heap = Heap()
b.unify(b, heap)
b.unify(Atom.newatom("hallo"), heap)
py.test.raises(UnificationFailed, b.unify, Atom.newatom("bye"), heap)
def test_var():
b = Var()
heap = Heap()
b.unify(Atom.newatom("hallo"), heap)
assert b.getvalue(heap).name == "hallo"
a = Var()
b = Var()
a.unify(b, heap)
a.unify(Atom.newatom("hallo"), heap)
assert a.getvalue(heap).name == "hallo"
assert b.getvalue(heap).name == "hallo"